Interfacial vibrational spectroscopy and Brewster angle microscopy distinguishing the interaction of terpineol in cell membrane models at the air-water interface

In this paper, gamma-terpineol, a known monoterpene with biological activity, including in lipidic interfaces, was incorporated in Langmuir monolayers of selected phospholipids as a model for cellular membranes. Surface pressure-area isotherms showed that selected amounts of gamma-terpineol expand DPPC and DPPE monolayers and decreased the monolayer elasticity, confirming the lipid/compound interaction. Characterization with vibrational spectroscopy and Brewster angle microscopy pointed that gamma-terpineol adsorbs on the polar heads of the phospholipids, affecting the gauche conformations of the aliphatic chains, and different patterns were observed for DPPC and DPPE monolayers, indicating a characteristic molecular accommodation of gamma-terpineol along the polar head of the phospholipids. Therefore, distinctive interactions with DPPC and DPPE could be observed regarding the incorporation of gamma-terpineol with each lipid, leading to particular molecular arrangements at the air-water interface and pointing the modulation of the interaction according to the chemical composition of the monolayer.